Tracheal aspirate levels of pro-inflammatory cytokines such as IL-6, IL-1β, TNF-α, and chemokines CCL2, CCL7, CCL8, and IL-8 (CXCL8) are higher in premature infants with respiratory distress syndrome who develop BPD (21–26). This evidence concerns the gene CCL2 and bronchopulmonary dysplasia.